Thailand Issues Heavy Rain and Flash Flood Warning for September 21–27

The Thai Meteorological Department (TMD) has released a seven-day forecast warning of significant weather instability across Thailand from September 21 to 27, 2026. According to Khaosod Online, the country is bracing for a new wave of heavy rainfall, with up to 80% of areas in the central region, including Bangkok and its vicinity, expected to be affected.

From September 21–22, heavy rain is anticipated in the North, lower Northeast, Central, East, and upper South regions. The weather pattern is driven by a monsoon trough interacting with a low-pressure system in the South China Sea. By September 23–27, conditions are expected to intensify as a strong low-pressure system moves from the coast of Vietnam into Thailand, bringing heavy to very heavy rainfall to the lower North, lower Northeast, Central, East, and upper South.

For travelers and residents, this weather poses a risk of flash floods and forest runoff. Maritime conditions are also affected; the upper Andaman Sea and upper Gulf of Thailand are experiencing waves of 1–2 meters, which may exceed 2 meters in areas with thunderstorms. Mariners are advised to exercise extreme caution and avoid sailing in stormy conditions. While the TMD has provided this outlook, residents should monitor local updates for specific provincial alerts, as the exact path and intensity of the low-pressure system remain subject to change.